Techniques of polymerizing styrene and acrylonitrile in an aqueous media are well known. Two of these techniques are emulsion polymerization and suspension polymerization. In the case of most emulsion polymerization systems, initiation and growth of polymer molecules occurs predominately in surfactant micelles or in aqueous solution and the resulting polymer dispersion (latex) is of relatively small particle size (e.g. 0.01 to 1 .mu.m). In a suspension polymerization system, initiation and growth of polymer molecules occurs predominantly in the monomer droplets and the resulting polymer dispersion (suspension) is of relatively large particle size (e.g. 20-2,000 .mu.m).